Less than two months ago, few of us had ever heard of the Weeknd. Then, as soon as the creepy R&B tracks from this free mixtape began to circulate, the hype engine revved up. There was the Drake cosign, the album art that looked like Spiritualized crossed with Tumblr art-p**n, the missing vowel, the stylish samples, and the project’s creators hiding in the shadows. You can’t buy buzz like this, and the Weeknd’s quick rise to Internet fame, both in indie circles and in parts of the mainstream, raised fascinating questions about the blurrier-than-ever lines between those two audiences and the underground’s newfound embrace of R&B.